While a company derives some benefit if an employee is unable to exercise options that are "in the money" -- such as an option price of $5 and market price of $100 -- as it theoretically could sell the same new shares and get $95 more for them, unless you are talking about LARGE numbers of options it likely would have little impact on the financial statements or perceived value of the company as such.
Absent an employment agreement Companies essentially have the right to fire at will, for other than prohibited forms of discrimination -- age, sex, race, etc. -- and option holders, as such are not in a protected class.